Exercise: Creating user table row

As a continuation of the previous exercise, you decided to define a function that generates a table with user details. This is how you implemented it:

fun userTable(users: List<User>): TableBuilder = table {
    tr {
        td { +"Id" }
        td { +"Name" }
        td { +"Points" }
        td { +"Category" }
    }
    for (user in users) {
        userRow(user)
    }
}

The only thing left is to define userRow function. This is your task. It should generate a table row with user details. This is how it should work:

val users = listOf(
    User("1", "Randy", 2, "A"),
    User("4", "Andy", 4, "B"),
    User("3", "Mandy", 1, "C"),
    User("5", "Cindy", 5, "A"),
    User("2", "Lindy", 3, "B"),
)
val table = userTable(users)
println(table)
// <table>
// <tr><td>Id</td><td>Name</td>
// <td>Points</td><td>Category</td></tr>
// <tr><td>1</td><td>Randy</td><td>2</td><td>A</td></tr>
// <tr><td>4</td><td>Andy</td><td>4</td><td>B</td></tr>
// <tr><td>3</td><td>Mandy</td><td>1</td><td>C</td></tr>
// <tr><td>5</td><td>Cindy</td><td>5</td><td>A</td></tr>
// <tr><td>2</td><td>Lindy</td><td>3</td><td>B</td></tr>
// </table>

This problem can either be solved in the below playground or you can clone kotlin-exercises project and solve it locally. In the project, you can find code template for this exercise in functional/dsl/UsersTable.kt. You can find there example usage and unit tests.

Once you are done with the exercise, you can check your solution here.

Playground

import org.junit.Test
import kotlin.test.assertEquals

data class User(val id: String, val name: String, val points: Int, val category: String)

fun userTable(users: List<User>): TableBuilder = table {
    tr {
        td { +"Id" }
        td { +"Name" }
        td { +"Points" }
        td { +"Category" }
    }
    for (user in users) {
        userRow(user)
    }
}

// TODO

fun main() {
    val users = listOf(
        User("1", "Randy", 2, "A"),
        User("4", "Andy", 4, "B"),
        User("3", "Mandy", 1, "C"),
        User("5", "Cindy", 5, "A"),
        User("2", "Lindy", 3, "B"),
    )
    // val table = userTable(users)
    // println(table)
    // <table>
    // <tr><td>Id</td><td>Name</td>
    // <td>Points</td><td>Category</td></tr>
    // <tr><td>1</td><td>Randy</td><td>2</td><td>A</td></tr>
    // <tr><td>4</td><td>Andy</td><td>4</td><td>B</td></tr>
    // <tr><td>3</td><td>Mandy</td><td>1</td><td>C</td></tr>
    // <tr><td>5</td><td>Cindy</td><td>5</td><td>A</td></tr>
    // <tr><td>2</td><td>Lindy</td><td>3</td><td>B</td></tr>
    // </table>
}

fun table(init: TableBuilder.() -> Unit): TableBuilder =
    TableBuilder().apply(init)

data class TableBuilder(
    var trs: List<TrBuilder> = emptyList()
) {
    fun tr(init: TrBuilder.() -> Unit) {
        trs += TrBuilder().apply(init)
    }

    override fun toString(): String =
        "<table>${trs.joinToString(separator = "")}</table>"
}

data class TrBuilder(
    var tds: List<TdBuilder> = emptyList()
) {
    fun td(init: TdBuilder.() -> Unit) {
        tds += TdBuilder().apply(init)
    }

    override fun toString(): String =
        "<tr>${tds.joinToString(separator = "")}</tr>"
}

data class TdBuilder(var text: String = "") {
    operator fun String.unaryPlus() {
        text += this
    }

    override fun toString(): String = "<td>$text</td>"
}

class StudentTableTest {
    @Test
    fun `should work for empty list`() {
        // when
        val result = userTable(listOf())

        // then
        val expected = TableBuilder().apply {
            trs += TrBuilder().apply {
                tds += TdBuilder().apply { text = "Id" }
                tds += TdBuilder().apply { text = "Name" }
                tds += TdBuilder().apply { text = "Points" }
                tds += TdBuilder().apply { text = "Category" }
            }
        }
        assertEquals(expected, result)
    }

    @Test
    fun `should work for a list with a single element`() {
        // given
        val users = listOf(
            User("1", "Randy", 2, "A"),
        )

        // when
        val result = userTable(users)

        // then
        val expected = TableBuilder().apply {
            trs += TrBuilder().apply {
                tds += TdBuilder().apply { text = "Id" }
                tds += TdBuilder().apply { text = "Name" }
                tds += TdBuilder().apply { text = "Points" }
                tds += TdBuilder().apply { text = "Category" }
            }
            trs += TrBuilder().apply {
                tds += TdBuilder().apply { text = "1" }
                tds += TdBuilder().apply { text = "Randy" }
                tds += TdBuilder().apply { text = "2" }
                tds += TdBuilder().apply { text = "A" }
            }
        }
        assertEquals(expected, result)
    }

    @Test
    fun `should work for a list with multiple users`() {
        // given
        val users = listOf(
            User("1", "Randy", 2, "A"),
            User("4", "Andy", 4, "B"),
            User("3", "Mandy", 1, "C"),
            User("5", "Cindy", 5, "A"),
            User("2", "Lindy", 3, "B"),
        )

        // when
        val result = userTable(users)

        // then
        val expected = TableBuilder().apply {
            trs += TrBuilder().apply {
                tds += TdBuilder().apply { text = "Id" }
                tds += TdBuilder().apply { text = "Name" }
                tds += TdBuilder().apply { text = "Points" }
                tds += TdBuilder().apply { text = "Category" }
            }
            for (user in users) {
                trs += TrBuilder().apply {
                    tds += TdBuilder().apply { text = user.id }
                    tds += TdBuilder().apply { text = user.name }
                    tds += TdBuilder().apply { text = user.points.toString() }
                    tds += TdBuilder().apply { text = user.category }
                }
            }
        }
        assertEquals(expected, result)
    }
}